Electron discharge device



mm Dec. 3, 19 6 amc'mou mscmaca nsvi'ca Robert L. Vance, Bell TelephoneWeehawken, N. 3., assignor to Labor-a toriea, Incorporated, New

.York, N. Y., a corporation of NewYork Application April 17, 1042,Serial-No. 439,375

40mm. (onto-27.5

This invention relates to electron discharge devices and moreparticularly to such devices operable at very high frequencies, such asfrequencies correspondingto wave-lengths in the cen-, timeter range, andembodying cavity resonatorv type circuits associated with theelectrodes.

In one form of ultra-short wave electron discharge device of the generalconstruction dis-- closed in the application Serial No. '388,043, flledApril 11, 1941, of John R. Pierce, a cavity reso Theinvention and theabove-notedg nd other features thereof will be understood more clearlyand fully from the following detailed description with referenceto theaccompanying drawing in which:

Fig.1 is a side view mainly in section of an electron dischargedeviceillustrative of one embodiment of this invention: and

nator is provided within the enclosing vessel of the device, theresonator being defined by a pair of electrodes and a portion of theenclosing vesseL I The resonant frequency of such a resonator isdependent upon the form and dimensions of the resonator, and smallchanges in the form and dimensions are attended by relatively largechanges in the resonant frequency of the resonator.

Practical mechanical considerations and manufacturing tolerances do notallow ready design of such resonators to have the extremely accuratedetermination of the resonant frequency thereof necessary for optimumoperation of the device in the centimeter wave-length range.Furthermore, for any given device, capability of operation at anyfrequency within a relatively wide band of frequencies may be desirableand realization of this desideratum entails tuning of the resonator tothe desired operating frequency.

One object of this invention is to enable the accurate tuning of cavityresonators. More specifically, one object of this invention is tofacilitate the accurate tuning of cavity resonators in electrondischarge devices wherein the cavity resonant is within the enclosingvessel of the device.

One illustrative embodiment of this invention comprises an enclosingvessel including two hollow, for example cylindrical, sections of metalin end to end relation and joined at the juxtaposed ends by a flexiblemember, such as a metallic annulus which constitutes a wall portion ofthe enclosing vessel. A pair of electrodes are mounted within theenclosing vessel and related with the flexible member so as to definetherewith a cavity resonator.

In accordance with one feature of this invention, a linkage including atoggle element is provided external to the enclosing vessel and couplingthe two hollow sections, the toggle element being adjustable to effectflexure of theflexible member and thus to alter the form of thecavityresonator. In one specific form, this linkage comprises a pair of bandssecured to the hollow sections and connected by a toggle elementincluding a pair of strips mounted in face to face relation and having amicrometer screw threaded thereto whereby the strips may be bowedrelative to one another and the effective length of the toggle elementthereby adjusted.

Fig. 2 is an enlarged perspective view, partly in section, of the deviceillustrated in Fig. 1 showing the cavity resonator defining elements andthe tuning mechanism therefor.

Referring now to the drawing, the electron discharge deviceillustratedin Fig. 1 comprises an enclosing vessel includinga metallic shell havinga cylindrical portion Ill and an inverted cupshaped portion ll coaxialwith the portion In and joined thereto by a flexible, metallic annularwall member l2, which may be integral with the cup-shaped portion II asshown. The cylindrical portion l 0 is closed at one end by a base orheader l3, for example of metal, having hermeticallyjoined thereto aplurality of metal eyelets l4 through'which leading-in conductors l5extend and to which the conductors are sealed hermetically by vitreousbeads l6. Also secured to the base or header is a coaxial transmissionline which includes an outer tubular conductor I1 and an inner conductorl8 hermetically sealedto an eyelet I9 by a vitreous bead 20, the innerconductor i8 being looped at its inner end as shown at 2i and connectedto the outer conductor I! at the inner end thereof.

The cup-shaped portion II has hermetically joined thereto a metalliceyelet 22 through which a leading-in conductor 23 extends, the conductor23 being sealed hermetically to the eyelet 22 by a vitreous bead. Seatedupon and secured to the end wall of the cup-shaped portion H is acup-shaped metallic shield or support 25.

Mounted upon the base or header I3 is an electron gun which comprises acylindrical indirectly heated cathode 26 having an electron emissivesurface 21 and a cylindrical beam-forming electrode 28 coaxial with andencompassing the cathode, the beam-forming electrode having a flaredinner end 28.

As shown clearly in Fig. 2, the metallic portion 10 of the enclosingvessel is provided with an inwardly extending annular flange 30underlying the flexible wall member l2, and having a centraltubularportion 3| across which a dished grid 32 extends. The flange 3'0is provided with an aperture in which the outer coaxial conductor i1 isfitted.

Mounted within the cup-shaped portion l l is an annular metallic support33 which carries a dished grid 34 opposite and axially aligned with thegrid 32 and conforming thereto.

The leading-in conductor 23 supports a metallic bridge or yoke 35 whichmounts a dished target or reflecting electrode opposite and in alignmentwith the grid 34. p

The grids 32 and'34 together with the. supp rts 30, 3| and 33 thereforand the annular wall l2 define a cavity resonator which is excitedduring the operation of the device and from which energy may be taken byway of the coaxial transmission line l1, l3,

During operation of the device, for example, as an oscillationgenerator, the electrons emanating -from the cathode surface 2! areconcentrated into a beam which isprojected through the grids 32 and 34and toward the target or reflecting electrode 36. In traversing the gapbetween the grids 32 and 34, the electrons are influenced by the highfrequencyfield between these grids and are thus velocity varied so thatthe-beam issuing from the grid 34 is composed of accelerated anddecelerated electrons. In the space between the grid 34 and the targetor reflecting electrode 36., the electrons are reversed in direction andare then projected in time spaced groups back into the gap between thegrids in such phase relation as to deliver energy to the field withinthe cavity resonator whereby oscillations are produced and sustained.

The frequency of these oscillations will be dependent upon, among otherfactors, the resonant frequency of the cavity resonator. Eflicientoperation requires that this resonator be tuned accurately to thedesired operating frequency. This invention enables the realization notonly of such accurate tuning but also thereof in an expeditious manner.

The metallic portions I and -II are coupled by a linkage of adjustablelength whereby relative axial movement between the portions I 0 and I Iof the enclosing vessel may be effected and, due to the flexure of theannular wall l2 and attendant relative movement between the grids 32 and34, the configuration of the cavity resonator may be altered with a.consequent change in the resonant frequency of the resonator. As shownparticularly clearly in- Fig. 2, this coupling linkage includes ametallic band 31 and 3 metal strips 38 secured to the shield 25 and theportion In of the enclosing vessel respectively. The band and strips arejoined by a metallic strip 39 aifixed thereto and by a toggle elementincluding a pair of metallic strips 40 and 4| mounted in face to facerelation and having a right-hand left-hand micrometer screw 42,extending therethrough and threaded to nuts 43 afllxed, as by welding,to the strips 40 and 4 I.

Rotation of the screw 42 results in relative movement of the strips 40'and 4| to bow the strips either toward or away from one another. Suchbowing of the strips results in a, change in the effective length of thetoggle element with a cor- 4 Although a specific embodiment of theinvention has been shown and described, it will be understood thatvarious modifications maybe made therein without departing from thescope and spirit of this invention as defined in the appended claims.

What is claimed is:

1. An electron discharge device comprising an enclosing vessel includinga pair of spaced portions mounted in end to end relation and a flexiblemember connecting said portions, means including said flexible memberdefining a cavity resonator within said vessel, said cavity resonatorhaving. an aperture therein, electrode means adjacent thereto-forexciting saidresonator, and means for tuning said resonator, said tuningmeans including a pair of adjacent flexible members extending betweensaid spaced portions and afllxed thereto and means coupled thereto foradjustably flexing said'adjacent flexible members.

2. An electron discharge device comprising an enclosing vessel includinga pair of hollow portions mounted in end 'to end relation and a flexiblemember connecting the opposed ends of said portions, means bounding acavity resonator within said vessel, said means including an electrodesupported from one of said hollow portions and asecond electrodesupported from the other of said hollow portions, electrode meansadjacent thereto for energizing said resonator and means for tuning saidresonator, said tuning means comprising a pair of adjacent strip membersextending between and having their ends secured to said hollow portionsand means coupled thereto for adjustably bowing said strip members.

3. An electron discharge device comprising a pair of members havingjuxtaposed electrode portions, means including said members and aflexible wall member defining a cavity resonator, said flexible wallmember extending between and connecting said pair of members, electrodemeans adjacent thereto for energizing. said cavity resonator, and meansfor tuningsaid resonator,

said tuning means comprising a pair of strip bers, means bounding acavity resonator within responding relative movement between theportions I0 and I I of the enclosing vessel and flexure of the annularwall I2,- and an attendant change in the resonant frequency of thecavity resonator.

It will be appreciated that very fine and accurate tuning of theresonator is thus enabled said vessel, said means including saidflexible wall, an electrode mounted from one of said hollow members anda second electrode in juxtaposition to said first electrode and mountedfrom the other of said hollow members, one of said electrodes having anapertured portion, means within said vessel for projecting an electronstream into said resonator through said apertured portion, and means fortuning said resonator, said tuning means comprising a pair of bands eachsecured to a corresponding one of said hollow members; a pair ofadjacent strip members mounted in face to face relation and secured attheir ends to said bands, and a micrometer screw threadably coupled toboth of said strip members and effective to flex said strip membersrelative to one another.

ROBERT L. VANCE.

